Electromagnet and annunciator.



UNITE STATES PATENT OFFICE.

CHARLES E. SCRIBNER, OF CHICAGO, AND FRANK R. MOBERTY, OF DOWNERS GROVE, ILLINOIS, ASSIGNORS TO THE WESTERN ELECTRIC COMPANY, OF

CHICAGO, ILLINOIS.

ELECTROMAGNETAND ANNUNCIATOR.

SPECIFICATION formingpart of Letters Patent N 0. 673,628, dated May 7, 1901.

Application filed April 6, 1893. Serial No. 469,268. (No model.)

To all whom it may concern:

Be it known that we, CHARLES E. SORIBNER, residing at Chicago, in the county of Cook, and FRANK R. MOBERTY, residing at Downers Grove, in the county of Dupage, State of Illinois, citizens of the United States, have invented a certain new and useful Improvement in Electromagnets and Annunciators, (Case No. 321,) of which the following is a full, clear, concise, and exact description, reference being had to the accompanying drawings, forming a part of this specification.

Our invention relates to electromagnets having movable armatures, and comprises,

first, a closed conducting-circuit formed of a mass of metal, as copper, having low magnetic permeability and surroundinga portion of the magnetic circuit of the electromagnet.

Second. Our invention consists in the combination, with an electromagnet, of a movable armature therefor adapted to form a part of the magnetic circuit of the electromagnet and a bridge of magnetic material shunting.

the armature to complete the magnetic cir- 2 5 cuit of the electromagnet.

Third. Our invention consists in the combination,witl1 the armature of the electromagnet, of a bridge of magnetic material adapted to shunt the said armature to complete the 0 magnetic circuit and a closed cond noting-circuit formed of a mass of metal of low magnetic permeabilityencircling a portion of the said magnetic circuit, whereby the armature is attracted when the helix of the magnet is traversed by current of constant direction, but not attracted when the helix is traversed by alternating current.

' Fourth. Our invention consists in the combination, with the core and armature of an electromagnet, of a mass of metal of low magnetic permeability adapted to be threaded by the magnetic lines of force of the magnet and means for closing at will either current of constant direction or alternating current 5 through the magnet, whereby the pole of the magnet presented to'the armature is excited only by current of constant direction.

Our invention, as will be readily under-' stood, maybe applied in various ways. In our present application we will describe the same applied to an individual annunciator for telephone-exchange systems. This annunciator is of the automatic or self-restoring type, and its construction is such that the shutter will be thrown down when the magnet is traversed by alternating current and restored by continuous current. By continuous current is meant such a current as is produced from a battery or by a continuous current dynamo machine, as distin- 6o guished from current of the alternating type or current of the pulsating type,in which the pulsations follow each other very rapidly, so as to approach the characteristic eifects of the alternating current. 5

In the accompanying drawings, which are illustrative of our invention, Figure l is a plan view of an electromagnet embodying our invention, with a diagram illustrative of means for sending current of different char- 7o acteristics through the magnet-coils. Fig. 2 is a side elevation of the electromagnet. Fig.

3 is a side elevation of an individual annunciatorprovided with our improvement. Fig.

& is a vertical longitudinal central section of said individual annunciator. Fig. 5 is a perspective view illustrative of the bridge of magnetic material for shunting the armature to complete the magnetic circuit. Fig. 6 is a sectional View of the shell, the copper. cyl- 8o inder, and the core of the annunciator, taken on line 3 3 of Fig. 3.

Like parts are referred to by similar letters of reference throughout the different figures.

We will first describe our invention gener- 8 5 ally, as illustrated in Figs. 1 and 2, and then will describe a special application thereof to individual annunciators, as embodied in Figs.

3 and 4.

The electromagnet of Figs. 1 and 2 is of the 0 horseshoe type, the soft-iron cores a a being provided each with a coil or helix of wire and connected together by the heel-bar b. The movable armature c is pivotally mounted in front of the poles, as is usual. The magnetic circuit of this electromagnet may be considered as passing from one core through the armature c to the other core and thence to the heel-bar, and from the heel-bar to the first core, thus completing the magnetic circuit.

Our invention consists in surrounding some portion of this'magnetic circuit with a mass of metal of low magnetic permeability, so that the magnetic lines of force in this magnetic circuit will thread such mass of metal, and as an adjunct to or special feature of our invention we-provide a magnetic bridge which shall shunt a portion of the magnetic lines of force from the armature. of metal of low magnetic permeability consists of two copper rings at e, the ring e being shown in section. These cylinders or rings are placed, as shown, upon the cores. The bridge f is of ironand placed as shown, so as to connect the ends of the cores together, and thus shunt a portion of the magnetic lines of force from the movable armature. The alternating-current generator g is placed in a circuit provided with a key 9', on closing which the coils of the magnet will be traversed by alternating current. The battery g may be connected in a similar way with the magnet by closing the key 9 Thus when the key g is closed continuous current will be sent through the magnet. A rheotome g is connected with a branch leading to battery g in which branch is included a key g so arranged that when said key g is closed pulsatory current will be produced and caused to traverse the coils of the electromagnet. When i the alternating current is closed through the coils of the armature, we find that the armature will not be attracted. When,

- however, the battery-current is directly closed to alternating current.

through the magnet, the poles of the magnet will be strongly excited and the armature will be attracted. In like manner, but not to the same degree, the armature will be attracted when the pulsatory current is closed through the magnet, as by depressing key 9 We find then in this electromagnet an armature which responds to continuous current and also, to avention illustrated in Figs. 1 and 2, is provided with certain mechanical features whereby it is adapted to be actuated by pulsating or alternating currents, butv to be retained inoperative, or having been operatedto be restored to its normal positionby continuous current.

In the self-restoring annunciator we employ a tubular electromagnet h, comprising a core h, a coil of wire 71, and an inclosing shell 71, At one end of the tubular magnet h is arranged a movable armature i, pivoted at its upper edge upon trunnions i, carried by brackets i secured to the shell k of the electromagnet. The armature 11 carries an arm i extending forward and terminating ina catch 1 At the forward end of the mag- In this instance the mass net ,h'is provided another armature-k, which is pivoted at' its lower edge upon trunnions it, carried by a bracket 10 secured to the shell h The trunnions k are placed a little to one side of the center of gravity of the shutter It, so thatthe latter tends to fall outward or away from the magnet. At the upper part of the bracket k are arran'ged'extensions or arms to which is hung-alight shield orapron l. The shutter 70 is normally engaged by: thecatch' '5 and prevented from falling; but when the catch is disengaged from it the shutter falls outward against the light shield land throws the latter into a horizontal position, disclosing the face of shutter '10, upon which any suitable number or indication may be painted. The fall of the shutter is at the same time'limited to a small angle, and it is prevented from moving to any considerable distance magnet h. 4

Surrounding the core 71/ of magnet h at the end toward the shutter 70 is a cylinder away from the poles of m, of copper, and outside of that, next the' armature la, is a thinsheet-iron disk n, like that shown in perspective of Fig. 5. When an alternating current is sent through-the coil 71, of'this ann unciator, the core 72/ is magnetized thereby, the magnetization being rapthat the alternating current passing through the coils causes magnetic efiects in the magnetic circuit, which by induction produces current in the circuit formed by the massof metal about the magnetic circuit. and that the secondary currents produced in the massof metal act in opposition to the primary alter- IIO nating currents upon the cores; or it may be said that the magnetic-force producedin the 1 circuit is expended in producing the secondary currents in the mass ofmetal of low magnetic permeability instead of in producing strong excitation of the poles of the magnet.

The fact that the armature 11 is strongly attracted by magnet h, while there is very little attraction upon armature It, indicates that lines-of force are induced in the core 71. by

the coil H, but that they do not pass through the core inclosed by tube on to the armature is. The lines of force induced by-coil 71, find ready circuit through a portion-of the core h, the armature t, and a portion of' the shell h but are prevented .from passing out through the armature k to complete their circuit and are compelled to escape acrossthe intervening space between the core and the shell without affecting the armature 70. When a continuous current is sent through the coil h no opposing current is generated in the cylinder an after the magnetization of the core has risen to its full amount, and the lines of force find a complete circuit through the core h, armature t', shell h and armature it. Both armatures are thus attracted, and if armature 7t has been released and has fallen it will be reattracted to its normal position and retained in that position. When the current in coil k is discontinued, the armature 2' is instantly released and allows the catch 1' to drop into position to engage the shutter it; but the cessation of the magnetism of core it induces a current in the cylinder m in the direction to continue the magnetism, and this eifects a continued attraction of the armatureh se' that the latter is released only an instant later when the catch has arrived in position to engage therewith.

The copper cylinder used without the iron disk produces an efiect similar to that obtained by the employment of both in conjunction, but of somewhat less degree. In the case of the last-described apparatus the device has a greater tendency to respond to pulsating currents of considerable fluctuation,since these then affect the copper cylinder in the same manner as the alternating currents, although in a much less degree, because the tendency of the magnet to retain its mag-- netization after the first pulsation of current through it is less on accdunt'of the absence of the completion of the magnetic circuit which was obtained by the use of the iron disk.

In the apparatus of Figs. 1 and 2 when a pulsating current of constant direction finds circuit through the coil the first pulsation of current acts at first to induce a current in cylinders 01 opposing the magnetization of the core; but, as is well known in the art, when the lines of force have been produced in a closed or nearly-closed magnetic circuit the iron retains nearly the full induction after the magnetizing force has been removed. Hence the second and subsequent currents in the same direction do not produce any considerable increase in magnetization in the core, and hence do not generate any considerable opposing current in the circuit formed by the cylinders d e. Thus the magnet becomes quite strongly magnetized, though not to the extent to which it is magnetized when the current is continuous, and attracts its armature to move the same to do the work required.

Having thus described ourinvention, what we claim as new, and desire to secure by Letters Patent, is-- l. The combination with an electromagnet, of a movable armature therefor adapted to form a part of the magnetic circuit of the electromagnet, a bridge of magnetic material partially shunting the armature to complete the magnetic circuit of the electromagnet,

and a closed conducting-circuit encircling some portion of the said magnetic circuit, whereby the electromagnet attracts its armature when energizedwith pulsating currents of constant direction, but fails to attract it when energized by alternating currents, substantially as described.

2. In an annunciator, the combination with the electromagnet thereof and the movable armature therefor, of a tube of conducting material surrounding the core of the electromagnet, a bridge, of magnetic material partially shunting the said armature, and an indicator adapted to be actuated by the movement of said armature, substantially as described.

3. The combination with a tubular electromagnet, of a tube of conducting material inclosing the core within the coil, a thin iron disk bridging the space between the core and the shell of the electromagnet near the poles thereof, a pivoted armature opposite the said poles, and an indicator controlled by said armature, substantially as described.

4. The combination with the core of an electromagnet, of an armature at each end thereof, and a conducting tube encircling said core near one of said armatures, whereby one armature only is attracted when alternating currents are sent through the electromagnet, but both are attracted when continuous currents traverse its coils, substantially as described.

5. In an automatically-restoring annunciator, the combination with the core of an electromagnet, of a movable armature at each end thereof, an indicator adapted to be dis played by the simultaneous movement of both .armatures, but to be replaced in its normal position by the action of a particular one, and a tube of conducting material encircling the core of said electromagnet near the armature which acts to replace the indicator, whereby the indicator is displayed when alternating currents find circuit through 'the device, but is replaced when a continuous current is sent through it, substantially as described.

6. The combination of an electromagnet having a winding adapted to be included in an electric circuit with a source of a continu ous current, and a source of alternating current, an armature for the magnet, and closed conducting-circuits encircling the pole-pieces of the said electromagnet, whereby the alternating current is prevented from efiecting the movement of the armature, as described.

In witness whereof .we hereunto subscribe our names this 30th day of March, A. D. 1893.

CHARLES E. SORIBNER. FRANK R. MOBERTY.

Witnesses:

ELLA EDLER, W. CLYDE JoNEs. 

